Bench-Stable, Substrate-Activated Cobalt Carboxylate Pre-Catalysts for Alkene Hydrosilylation with Tertiary Silanes

High-spin
pyridine diimine cobalt­(II) bis­(carboxylate) complexes
have been synthesized and exhibit high activity for the hydrosilylation
of a range of commercially relevant alkenes and tertiary silanes.
Previously observed dehydrogenative silylation is suppressed with
the use of sterically unencumbered ligands, affording exclusive hydrosilylation
with up to 4000 TON. The cobalt precatalysts were readily prepared
and handled on the benchtop and underwent substrate activation, obviating
the need for external reductants. The cobalt catalysts are tolerant
of epoxide, amino, carbonyl, and alkyl halide functional groups, broadening
the scope of alkene hydrosilylation with earth-abundant metal catalysts.

本研究合成了高自旋吡啶二亚胺双(羧酸根)合钴(II)配合物，该类配合物对一系列商业化相关的烯烃与叔硅烷的硅氢加成反应展现出优异的催化活性。此前报道的脱氢硅化副反应可通过使用位阻较小的配体得到有效抑制，最终实现专一性的硅氢加成反应，转化数（TON）最高可达4000。该钴基预催化剂制备简便，可在普通实验室台面上进行操作，且可通过底物活化完成催化循环，无需额外添加外部还原剂。该钴基催化剂对环氧基、氨基、羰基以及卤代烷基官能团均具有良好的耐受性，拓宽了地球丰产金属催化剂应用于烯烃硅氢加成反应的底物范围。